Open AccessOptimization of Citric Acid Production from Glucose by Yarrowia lipolytica
Author(s) -
Moeller L.,
Strehlitz B.,
Aurich A.,
Zehnsdorf A.,
Bley T.
Publication year - 2007
Publication title -
engineering in life sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.547
H-Index - 57
eISSN - 1618-2863
pISSN - 1618-0240
DOI - 10.1002/elsc.200620207
Subject(s) - yarrowia , citric acid , aspergillus niger , substrate (aquarium) , chemistry , yield (engineering) , bioprocess , food science , biochemistry , nuclear chemistry , chromatography , yeast , biology , materials science , ecology , paleontology , metallurgy
Citric acid (CA) is mainly produced in a biotechnological process using Aspergillus niger . In this process, large amounts of wastes have to be removed. Since the use of Yarrowia lipolytica for CA production is an environmental compatible alternative method, the CA production was optimized in regard to growth temperature and pH as well as substrate and product inhibition. The highest value of the maximum specific growth rate at pH 6.5 was found to be μ max = 0.192 h –1 , whereas the largest amount of CA of 24.91 g/L as well as the highest selectivity of the bioprocess (89.9 % CA) and the maximum yield (0.22 g CA /g Glucose ) were obtained at pH 6.0. During the growth phase, the temperature optimum was found to be in the range of 30–34 °C (μ max = 0.132 h –1 ). Nevertheless, the highest concentration of CA during the production phase was obtained at 30 °C (41 g/L CA, 93.1 % CA, 0.55 g CA /g glucose ). In studying the substrate inhibition of the process, a clear tendency of decrease in the maximum specific growth rate was detected when the initial glucose concentration was increased from 50 g/L (μ max = 0.17 h –1 ) to 200 g/L (μ max = 0.055 h –1 ). The addition of 120 g/L CA to the culture broth at the start of the production phase reduced the production of CA from 32.1 g/L to 7.4 g/L.